Organic electroluminescent display device and method of fabricating the same

ABSTRACT

An organic electroluminescent display device comprises a substrate, including a pixel region and a non-pixel region at a boundary of the pixel region; a first electrode on the substrate in the pixel region; a separator over the first electrode, the separator located in the non-pixel region, the separator including a first portion having a first width and a second portion having a second width smaller than the first width, the first portion overlapping edges of the first electrode, and the second portion within the non-pixel region; an organic electroluminescent layer over the separator in the pixel region surrounded by the separator; and a second electrode on an entire surface of the organic electroluminescent layer and the separator.

The present invention claims the benefit of Korean Patent ApplicationNo. 2003-0100668, filed in Korea on Dec. 30, 2003, which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device, and moreparticularly, an organic electroluminescent display device and a methodof fabricating the same.

2. Discussion of the Related Art

Generally, an organic electroluminescent display (OELD) device emitslight by injecting electrons from a cathode and holes from an anode intoan emission layer, combining the electrons with the holes, generatingexcitons, and transitioning the excitons from an excited state to aground state. In contrast to a liquid crystal display (LCD) device, anOELD does not require an additional light source because the OELD devicetransmits light emitted by the transition of the excitons betweenstates. Accordingly, the OELD device is lighter and smaller than acomparable liquid crystal display (LCD) device. The OELD device hasother desirable characteristics, such as low power consumption, superiorbrightness and a fast response time. Because of these advantageouscharacteristics, the OELD device is regarded as a promising candidatefor use in various next-generation consumer electronic applications,such as cellular phones, car navigation systems (CNS), personal digitalassistants (PDA), camcorders and palmtop computers. Moreover, an OELDdevice is much cheaper to produce than an LCD device because thefabrication process is relatively simpler for the OELD device than theLCD device and has fewer processing steps. There are two different typesof OELD devices: passive matrix and active matrix.

FIG. 1 is a cross-sectional view of an organic electroluminescent deviceaccording to a related art. Referring to FIG. 1, an OELD device 10includes a first substrate 12 and a second substrate 28 facing andspaced apart from each other. An array element layer 14 is formed on aninner surface of the first substrate 12. The array element layer 14includes including a thin film transistor (TFT) T. A first electrode 46,an organic electroluminescent (EL) layer 50, and a second electrode 52are sequentially formed over the array element layer 14. The organic ELlayer 50 may separately display red, green, and blue colors for eachpixel region P.

The first substrate 12 and the second substrate 28 are attached with asealant 26. The OELD device 10 is encapsulated by attaching the firstsubstrate 12 to the second substrate 28. A moisture absorbent desiccant22 is positioned on the second substrate 28. The moisture absorbentdesiccant 22 eliminates moisture and oxygen that may penetrate theencapsulated organic EL layer 50. More particularly, a portion of thesecond substrate 28 is etched and the moisture absorbent desiccant 22 isplaced in the etched portion and affixed by a holding element 25.Although not shown, the organic EL layer may be divided into a pluralityof pixel regions by a separator.

FIG. 2 is a plan view of a separator in an organic electroluminescentdevice according to the related art. Referring to FIG. 2, a firstelectrode 46 and an organic EL layer 50 (shown in FIG. 1) are located inthe pixel region P. A second electrode 52 (shown in FIG. 1) is formed onan entire surface of the first substrate 12. For example, when the firstelectrode 46 acts as an anode, it is formed by depositing and patterninga conductive material having a high work-function, such as indium tinoxide (ITO), through a vacuum apparatus, such as a sputtering chamber.In addition, when the organic EL layer 50 is made of a polymericmaterial, it is formed by a printing process, for example ink-jetprinting. On the other hand, when the organic EL layer 50 is made of amonomeric material, it is formed by a deposition process.

A separator SP is required to divide the organic EL layer 50 into aplurality of pixel regions P in an independent emitting type OELD deviceusing a polymeric organic EL material. The separator SP can preventmixing between different colors of the organic EL layers 50. Althoughnot shown, the buffer layer 48 and the separator SP correspond toportions of the gate, data and power lines.

The organic EL layer 50 includes red, green and blue EL layers (notshown) formed in the pixel regions P in repeating order after formingthe separator SP at a boundary of the pixel regions P and a buffer layer48 on the separator SP. The buffer layer 48 is located at the boundaryof the pixel regions P including a portion overlapping edges of thefirst electrode 46 to prevent any electrical contact between the firstelectrode 46 and the second electrode 52 (shown in FIG. 1) at the comerof the separator SP. Thus, the buffer layer 48 is larger than theseparator SP.

FIG. 3 is a plan view of an array substrate of an organicelectroluminescent device for one pixel region according to the relatedart. In general, an array element layer 14 (shown in FIG. 1) of an OELDdevice 10 includes a switching thin film transistor Ts, a driving thinfilm transistor TD and a storage capacitor CST. A first substrate 12 ismade of a transparent insulating substrate, such as glass and plastic. Agate line GL and a data line DL cross each other are formed on the firstsubstrate 12. The gate line GL and the data line DL define a pixelregion. An insulating layer (not shown) is interposed between the gateline GL and the data line DL. A power line PL crosses the gate line GL,in parallel with and spaced apart from the data line DL.

The switching thin film transistor Ts includes a switching gateelectrode 26, a switching active layer 16, a switching source electrode34, and a switching drain electrode 36. Similarly, the driving thin filmtransistor TD includes a driving gate electrode 28, a driving activelayer 18, a driving source electrode 38, and a driving drain electrode40. The switching gate electrode 26 is connected to the gate line GL andthe switching source electrode 34 is connected to the data line DL. Theswitching drain electrode 36 is connected to the driving gate electrode28 via a first contact hole 69 that exposes a portion of the drivinggate electrode 28. The driving source electrode 38 is connected to thepower line PL via a second contact hole 57 that exposes a portion of thepower line PL. Moreover, a first electrode 46 is connected to thedriving drain electrode 40 via the third contact hole 59. The power linePL overlaps a first capacitor electrode 20 with the insulating layerinterposed therebetween to form the storage capacitor CST.

Although not shown, the separator SP (shown in FIG. 2), which is formedin a portion corresponding to the data line DL and the power line PL,can divide the organic EL layer emitting a specific light into aplurality of pixel regions. Further, the buffer layer 48 (shown in FIG.2) is formed between the first electrode 46 and the separator SP and islocated in the non-pixel region at a boundary of the pixel region Pincluding the portion overlapping edges of the first electrode 46.

FIGS. 4A, 4B and 5 are cross-sectional views taken along lines IVA-IVA,IVB-IVB and V-V of FIG. 3, respectively. Referring to FIGS. 4A, 4B and5, a switching thin film transistor T_(S) and a driving thin filmtransistor T_(D) are formed on a first substrate 12 including aswitching region S and a driving region D within a pixel region P,respectively. The switching thin film transistor T_(S) includes aswitching active layer 16, a switching gate electrode 26, a switchingsource electrode 34, and a switching drain electrode 36. Similarly, thedriving thin film transistor T_(D) includes a driving active layer 18, adriving gate electrode 28, a driving source electrode 38, and a drivingdrain electrode 40.

Specifically, although not shown, the switching gate electrode 26 isconnected to the gate line GL and the switching source electrode 34 isconnected to the data line DL. The switching drain electrode 36 isconnected to the driving gate electrode 28. The driving source electrode38 is connected to the power line PL, and the driving drain electrode 40is connected to a first electrode 46 in the pixel region P. A bufferlayer 48 is formed on the first electrode 46 at a boundary of the pixelregion P corresponding to the data line DL and the power line PL, asshown in FIG. 5. The buffer layer 48 overlaps edges of the firstelectrode 46. A separator SP is formed on the buffer layer 48 within theboundary of the pixel region P. An organic EL layer 50 is formed on thefirst electrode 46 in the pixel region P surrounded by the separator SP.A second electrode 52 is formed on the entire surface of the organic ELlayer 50 and the separator SP. However, at least two mask processes arerequired to form the buffer layer 48 and the separator SP for the OELDdevice.

FIGS. 6A to 6E are cross-sectional views of a fabricating process of anorganic electroluminescent diode substrate for an organicelectroluminescent device according to the related art. Referring toFIG. 6A, a first electrode 46 is formed on a first substrate 12including a pixel region P. The first electrode 46 is located in thepixel region P. An inorganic material layer 47 is formed by depositingan inorganic material, such as silicon nitride (SiNx), on the entiresurface of the first electrode 46 and the first substrate 12. Aphotoresist layer 80 is formed by coating photoresist on the inorganicinsulating material layer 47.

Referring to FIG. 6B, a photoresist pattern 82 is formed by patterningthe photoresist layer 80 on the inorganic material layer 47 at theboundary of the pixel region P including a portion overlapping edges ofthe first electrode 46. Referring to FIG. 6C, a buffer layer 48 isformed by etching a portion of the inorganic material layer 47 (shown inFIG. 6B) uncovered by the photoresist pattern 82 (shown in FIG. 6B).Then, the buffer layer 48 is formed using a first mask process, whichincludes exposing, developing and etching. An organic layer 90 is formedby coating an organic insulating material on the entire surface of thebuffer layer 48 and the first electrode 46.

Referring to FIG. 6D, a separator SP is formed by patterning the organicmaterial layer 90 (shown in FIG. 6C) through a second mask processsimilar to the first mask process. The separator SP is located withinthe boundary of the pixel region P but the buffer layer 48 overlaps theedges of neighboring pixel regions P to prevent the first electrode 46and a second electrode that will be formed later from electricallycontacting each other. Thus, although not shown, a width of the bufferlayer 48 is larger than a width of the separator SP. When an organic ELlayer is formed by coating a polymeric material, the separator SP shouldhave a height of more than 1 micrometer. Thus, a portion of the organicEL layer near to the separator SP becomes thicker. Accordingly, theseparator SP should have a predetermined side gap K with the bufferlayer 48 toward the first electrode 46.

Referring to FIG. 6E, an organic EL layer 50 is formed on the firstelectrode 46 in the pixel region P surrounded by the separator SP. Asecond electrode 52 is formed on the entire surface of the organic ELlayer 50 and the separator SP. The second electrode 52 acts as a cathodeand comprises a metallic material having a low work-function, such ascalcium (Ca), aluminum (Al) and magnesium (Mg) and lithiumfluorine/aluminum (LiF/Al). In addition, when the organic EL layer 50 isformed by coating, no mask process is required for forming the organicEL layer 50.

At least two mask processes are required to form the buffer layer 48 andthe separator SP. As a result, several mask processes are required forthe entire manufacturing process. The defective fraction increases withthe number of mask processes. Moreover, production yield decreases andproduction cost increases because of processing delay, thus weakening acompetitive pricing of the EL device.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an OELD device and amethod of fabricating the same that substantially obviate one or more ofthe problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an OELD device that canreduce fabrication processing time and cost.

Another object of the present invention is to provide a method offabricating an OELD device that can reduce fabrication processing timeand cost.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a method offabricating an organic electroluminescent display device comprisesforming a first electrode in a pixel region of a substrate, thesubstrate including a non-pixel region at a boundary of the pixelregion; forming a resin solution layer by coating a resin solution onthe first electrode; pressing a mold on the resin solution layer, themold having a recessed portion alternating with a protruding portion,the recessed portion having the same height as the protruding portion,the recessed portion and the protruding portion facing the resinsolution layer, a first width of the recessed portion near to the resinsolution layer being larger than a second width of the recessed portionaway from the resin solution layer; solidifying the resin solution layerby heating; removing the mold from the solidified resin solution layerforming a separator in the non-pixel region on the substrate, theseparator having a first portion having the first width and a secondportion having the second width, the first portion overlapping edges ofthe first electrode, and the second portion within the non-pixel region;forming an organic electroluminescent layer on the first electrode inthe pixel region surrounded by the separator; and forming a secondelectrode on the organic electroluminescent layer and the separator.

In another aspect, a method of fabricating an organic electroluminescentdisplay device comprises forming a first electrode in a pixel region ofa substrate, the substrate including a non-pixel region at a boundary ofthe pixel region; forming a resin solution layer by coating a resinsolution on the first electrode; pressing a mold on the resin solutionlayer, the mold having a recessed portion alternating with a protrudingportion, the recessed portion having the same height as the protrudingportion, the recessed portion and the protruding portion facing theresin solution layer, the recessed portion and the protruding portionhaving respective square shapes; solidifying the resin solution layer bysequentially heating at two different temperatures including a firsttemperature smaller or equal to a boiling point of the resin solutionand a second temperature higher than the first temperature; removing themold from the solidified resin solution layer forming a separator in thenon-pixel region on the substrate, the separator having a first portionhaving a first width and a second portion having a second width smallerthan the first width, the first portion overlapping edges of the firstelectrode, and the second portion within the non-pixel region; formingan organic electroluminescent layer in the pixel region surrounded bythe separator; and forming a second electrode on the organicelectroluminescent layer and the separator.

In another aspect, a method of fabricating an organic electroluminescentdevice comprises forming a first electrode on the entire surface of afirst substrate including a pixel region and a non-pixel region at aboundary of the pixel region; form a resin solution layer by coating aresin solution on the entire surface of the first electrode; pressing amold on the resin solution layer under a predetermined pressure, themold including a recessed portion alternating with a protruding portion,the recessed portion having the same height as the protruding portion,the recessed portion and the protruding portion of the mold facing theresin solution layer, a width of the recessed portion graduallyincreasing toward the substrate and a width of the protruding portiongradually decreasing toward the substrate; solidifying the resinsolution layer by heating; removing the mold from the solidified resinsolution layer forming a separator in the non-pixel region on thesubstrate, the separator having a first portion having a first width anda second portion having a second width smaller than the first width, thefirst portion closer to the substrate than the second portion, across-sectional of the second portion decreasing gradually from both endsides thereof toward a middle part thereof; and sequentially forming anorganic electroluminescent layer and a second electrode on the firstelectrode, the organic electroluminescent layer and the second electrodedivided into a region corresponding to the pixel region by theseparator.

In another aspect, an organic electroluminescent display devicecomprises a substrate, including a pixel region and a non-pixel regionat a boundary of the pixel region; a first electrode on the substrate inthe pixel region; a separator over the first electrode, the separatorlocated in the non-pixel region, the separator including a first portionhaving a first width and a second portion having a second width smallerthan the first width, the first portion overlapping edges of the firstelectrode, and the second portion within the non-pixel region; anorganic electroluminescent layer over the separator in the pixel regionsurrounded by the separator; and a second electrode on the entiresurface of the organic electroluminescent layer and the separator.

In another aspect, an organic electroluminescent display devicecomprises a first substrate, including a pixel region and a non-pixelregion at a boundary of the pixel region; a first electrode on theentire surface of the first substrate; a separator over the firstelectrode in the non-pixel region, the separator having a first portionhaving a first width and a second portion having a second width smallerthan the first width, a cross-sectional of the second portion decreasinggradually from both end sides thereof toward a middle part thereof; anorganic electroluminescent layer over the separator, the organicelectroluminescent layer in the pixel region; and a second electrode onthe organic electroluminescent layer, the second electrode correspondingto the organic electroluminescent layer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a cross-sectional view of an organic electroluminescent deviceaccording to a related art.

FIG. 2 is a plan view of a separator in an organic electroluminescentdevice according to the related art.

FIG. 3 is a plan view of an array substrate of an organicelectroluminescent device for one pixel region according to the relatedart.

FIGS. 4A, 4B and 5 are cross-sectional views taken along lines IVA-IVA,IVB-IVB and V-V of FIG. 3, respectively.

FIGS. 6A to 6E are cross-sectional views of a fabricating process of anorganic electroluminescent diode substrate for an organicelectroluminescent device according to the related art.

FIG. 7A is a cross-sectional view of the formation of a pixel electrodeon a substrate in a process of fabricating an organic electroluminescentdevice according to a first embodiment of the present invention.

FIG. 7B is a cross-sectional view of the molding of a resin layer on asubstrate in a process of fabricating an organic electroluminescentdevice according to the first embodiment of the present invention.

FIG. 7C is a cross-sectional view of the formation of a separator on asubstrate in a process of fabricating an organic electroluminescentdevice according to the first embodiment of the present invention.

FIG. 7D is a cross-sectional view of the formation of an organicelectroluminescent layer on a substrate in a process of fabricating anorganic electroluminescent device according to the first embodiment ofthe present invention.

FIG. 8A is a cross-sectional view of the formation of a pixel electrodeon a substrate in a process of fabricating an organic electroluminescentdevice according to a second embodiment of the present invention.

FIG. 8B is a cross-sectional view of the molding of a resin layer on asubstrate in a process of fabricating an organic electroluminescentdevice according to the second embodiment of the present invention.

FIG. 8C is a cross-sectional view of the formation of a separator on asubstrate in a process of fabricating an organic electroluminescentdevice according to the second embodiment of the present invention.

FIG. 8D is a cross-sectional view of the formation of an organicelectroluminescent layer on a substrate in a process of fabricating anorganic electroluminescent device according to the second embodiment ofthe present invention.

FIG. 9 is a cross-sectional view of an exemplary dual-panel type organicelectroluminescent device according to a third embodiment of the presentinvention.

FIG. 10A is a cross-sectional view of the formation of a full-colorelement layer on a substrate in a process of fabricating an organicelectroluminescent diode substrate for a dual-panel type organicelectroluminescent device according to the third embodiment of thepresent invention.

FIG. 10B is a cross-sectional view of the molding of a resin layer on anelectrode in a process of fabricating an organic electroluminescentdiode substrate for a dual-panel type organic electroluminescent deviceaccording to the third embodiment of the present invention.

FIG. 10C is a cross-sectional view of the formation of a separator on anelectrode in a process of fabricating an organic electroluminescentdiode substrate for a dual-panel type organic electroluminescent deviceaccording to the third embodiment of the present invention.

FIG. 10D is a cross-sectional view of the formation of an organicelectroluminescent layer on an electrode in a process of fabricating anorganic electroluminescent diode substrate for a dual-panel type organicelectroluminescent device according to the third embodiment of thepresent invention.

FIG. 11 is a scanning electron microscopic view of an exemplaryseparator manufactured in accordance with the third embodiment of thepresent invention.

FIGS. 12A and 12B are cross-sectional views of an array substrate for adual-panel type organic electroluminescent device according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIG. 7A is a cross-sectional view of the formation of a pixel electrodeon a substrate in a process of fabricating an organic electroluminescentdevice according to a first embodiment of the present invention.Referring to FIG. 7A, a substrate 100 includes a pixel region P, and anon-pixel region NP at a boundary of the pixel region P. A firstelectrode 102 is formed on the substrate 100. The first electrode 102 islocated in the pixel region P. For example, when the first electrode 102acts as an anode, it is made of a conductive material having a highwork-function, such as indium tin oxide (ITO). Then, a resin solutionlayer 104 is formed on the entire surface of the substrate 100 includingthe first electrode 102 by coating the entire surface of the substrate100 and the first electrode 102 with a resin solution. The coatingprocess may be performed by dipping the substrate in the resin solution.Alternatively, the coating process may be performed by dropping theresin solution on the substrate. The resin solution may include atransparent organic material, such as acrylic resin.

FIG. 7B is a cross-sectional view of the molding of a resin layer on asubstrate in a process of fabricating an organic electroluminescentdevice according to the first embodiment of the present invention.Referring to FIG. 7B, a mold M1 is prepared. The mold M1 has a recessedportion RP alternating with a protruding portion PP. The recessedportion RP has the same height H1 as the protruding portion PP. The moldM1 is slightly pressed on the resin solution layer 104, with therecessed portion RP and the protruding portion PP of the mold M1 facingthe resin solution layer 104. The recessed portion RP has a firstportion having a first width W1 and a second portion having a secondwidth W2. The first portion is closer to the resin solution layer 104than the second portion. The second width W2 is smaller than the firstwidth W1. A portion of the resin solution layer 104 corresponding to therecessed portion RP of the mold M1 become a separator at a later stagein the manufacturing process.

In an embodiment of the invention, recessed and protruding patterns forthe mold M1 maybe formed using a soft molding method. In this case, themold M1 is formed by filling an elastomeric in a predetermined moldframe. For example, the elastomeric includes one of polydimethylsiloxane(PDMS), polyurethane and polyimide.

When the mold M1 is slightly pressed against the resin solution layer104, a portion of the resin solution layer 104 contacting the protrudingportion PP of the mold M1 is moved toward the recessed portion RP due toa repulsion between the mold M1 and the resin solution layer 104. Thus,the portion of the resin solution layer 104 contacting the protrudingportion PP of the mold M1 fills the inner part of the recessed portionRP of the mold M1. Then, the resin solution layer 104 is solidified byheating it. Heating may be performed at a temperature higher than aboiling point and a transition temperature of the resin solution.

FIG. 7C is a cross-sectional view of the formation of a separator on asubstrate in a process of fabricating an organic electroluminescentdevice according to the first embodiment of the present invention.Referring to FIG. 7C, the mold M1 (shown in FIG. 7B) is removed, leavingthe solidified molded resin solution layer on the substrate 100. Thesolidified molded resin solution layer forms a separator 106 on thesubstrate 100. The separator 106 has a first portion BB having the firstwidth W1 and a second portion SS having the second width W2. The firstportion BB of the separator 106 overlaps edges of the first electrode102. The second portion SS of the separator 106 is located within thenon-pixel region P. The first portion BB acts as a buffer layer and thesecond portion SS acts as a substantial separator means.

The first width W1 of the first portion BB is larger than the secondwidth W2 of the second portion SS. A side gap K between the first widthW1 and the second width W2 is between 2 micrometers and 10 micrometers,a thickness KK of the first portion BB of the separator 106 is less thanabout 300 nanometers. A side of the second portion SS is perpendicularto a surface of the substrate 100.

FIG. 7D is a cross-sectional view of the formation of an organicelectroluminescent layer on a substrate in a process of fabricating anorganic electroluminescent device according to the first embodiment ofthe present invention. Referring to FIG. 7D, at least one organicelectroluminescent (EL) layer 108 is formed on the first electrode 102in the pixel region P surrounded by the separator 106. Forming theorganic EL layer 108 includes forming red, green and blue EL layers (notshown) in the pixel regions P in repeating orders. The at least oneorganic EL layer 108 may be a single layer or may include multiplelayers. When the at least one organic EL layer 108 includes multiplelayers and the first electrode 102 acts as the anode, the at least oneorganic EL layer 108 includes a hole transporting layer 108 a on thefirst electrode 102, an emitting layer 108 b and an electrontransporting layer 108 c on a later-formed second electrode.

A second electrode 110 is formed on the entire surface of the organic ELlayer 108 and the separator 106. When the second electrode 110 acts as acathode, it includes a metallic material, such as calcium (Ca), aluminum(Al) and magnesium (Mg) and lithium fluorine/aluminum (LiF/Al). Thefirst electrode 102, the organic EL layer 108 and the second electrode110 form an organic EL diode D_(EL).

FIG. 8A is a cross-sectional view of the formation of a pixel electrodeon a substrate in a process of fabricating an organic electroluminescentdevice according to a second embodiment of the present invention.Referring to FIG. 8A, a substrate 200 includes a pixel region P, and anon-pixel region NP at a boundary of the pixel region P. A firstelectrode 202 is formed on the substrate 200. The first electrode 202 islocated in the pixel region P. Then, a resin solution is coated on theentire surface of the substrate 200 including the first electrode 202 toform a resin solution layer 204. The resin solution may include atransparent organic material, such as acrylic resin.

FIG. 8B is a cross-sectional view of the molding of a resin layer on asubstrate in a process of fabricating an organic electroluminescentdevice according to the second embodiment of the present invention.Referring to FIG. 8B, a mold M2 is prepared. The mold M2 has a recessedportion RP alternating with a protruding portion PP. The recessedportion RP has the same height H2 as the protruding portion PP. Therecessed portion RP and the protruding portion PP may each have a squareshape. The mold M2 is slightly pressed on the resin solution layer 204.

When the mold M2 is slightly pressed against the resin solution layer204, a portion of the resin solution layer 204 contacting the protrudingportion PP of the mold M2 is moved toward the recessed portion RP due toa repulsion between the mold M2 and the resin solution layer 204. Thus,the portion of the resin solution layer 204 contacting the protrudingportion PP of the mold M2 fills the inner part of the recessed portionRP of the mold M2. Then, the resin solution layer 204 is solidified byheating it. Heating may be performed at two different temperaturesincluding a first temperature smaller than or equal to a boiling pointof the resin solution of the resin solution layer 204, and a secondtemperature higher than the first temperature.

FIG. 8C is a cross-sectional view of the formation of a separator on asubstrate in a process of fabricating an organic electroluminescentdevice according to the second embodiment of the present invention.Referring to FIG. 8C, the mold M2 (shown in FIG. 8B) is removed, leavingthe solidified molded resin solution layer on the substrate 200. Thesolidified molded resin solution layer forms a separator 206 on thesubstrate 200. The separator 206 has a first portion BB having the firstwidth W1 and a second portion SS having the second width W2. The firstportion BB of the separator 206 overlaps edges of the first electrode202. The second portion SS of the separator 206 is located within thenon-pixel region P.

The first portion BB acts as a buffer layer and the second portion SSacts as a substantial separator means. The first width W1 of the firstportion BB is larger than the second width W2 of the second portion SS.A side gap K between the first width W1 and the second width W2 isbetween 2 micrometers and 10 micrometers, a thickness KK of the firstportion BB of the separator 206 is less than about 300 nanometers.

FIG. 8D is a cross-sectional view of the formation of an organicelectroluminescent layer on a substrate in a process of fabricating anorganic electroluminescent device according to the second embodiment ofthe present invention. Referring to FIG. 8D, at least one organicelectroluminescent (EL) layer 208 is formed on the first electrode 202in the pixel region P surrounded by the separator 206. Forming theorganic EL layer 208 includes forming red, green and blue EL layers (notshown) in the pixel regions P in repeating order. The at least oneorganic EL layer 208 may be a single layer or may include multiplelayers. When the at least one organic EL layer 208 includes multiplelayers and the first electrode 202 acts as the anode, the at least oneorganic EL layer 208 includes a hole transporting layer 208 a on thefirst electrode 202, an emitting layer 208 b and an electrontransporting layer 208 c on a later-formed second electrode.

A second electrode 210 is formed on the entire surface of the organic ELlayer 208 and the separator 206. When the second electrode 210 acts as acathode, it includes a metallic material, such as calcium (Ca), aluminum(Al) and magnesium (Mg) and lithium fluorine/aluminum (LiF/Al). Thefirst electrode 202, the organic EL layer 208 and the second electrode210 form an organic EL diode DEL. Although not shown, an array elementlayer including a gate line, a data line, a power line and a thin filmtransistor may be formed between the substrate 200 and the organic ELdiode D_(EL).

Hereinafter, a dual-panel type OELD device will be described, in whichan array element layer and an organic EL diode are formed on theirrespective substrates. A method of fabricating a dual-panel type OELDdevice will also be described, which can reduce processing time and costby providing a separator that functions as a buffer.

FIG. 9 is a cross-sectional view of an exemplary dual-panel type organicelectroluminescent device according to a third embodiment of the presentinvention. Referring to FIG. 9, first and second substrates 300 and 400including a plurality of pixel regions P face each other and are spacedapart from each other. A full-color element layer FE is formed on thesecond substrate 400. Specifically, the full-color element layer FEincludes a color filter layer 404 on the second substrate 400 in thepixel region P, a color changing medium 405 on the color filter layer404, a black matrix 402 on the second substrate 400 at a boundary of thecolor filter layer 404 and the color changing medium 405, and anovercoat layer 406 covering the entire surface of the black matrix 402,the color changing medium 405 and the color filter layer 404. The colorfilter layer 404 includes red, green and blue sub-color filters (notshown). The color changing medium 405 includes red, green and blue colorchanging media (not shown) corresponding to the red, green and bluesub-color filters, respectively. The overcoat layer 406 may include anorganic insulating material, such as benzocyclobutene (BCB),polyacrylate, polyimide and polyamide.

A first electrode 408 is formed on the overcoat layer 406. A separator410 is formed over the first electrode 408 at the boundary of the pixelregion P. An organic EL layer 412 and a second electrode 414 are formedon the first electrode 408 in the pixel region P surrounded by theseparator 410. When the first electrode 408 acts as an anode and thesecond electrode 414 acts as a cathode, the first electrode 408 mayinclude a conductive material, such as indium tin oxide (ITO), and thesecond electrode 414 may include a metallic material, such as calcium(Ca), aluminum (Al) and magnesium (Mg), and lithium fluorine/aluminum(LiF/Al). The first electrode 408, the organic EL layer 412 and thesecond electrode 414 form an organic EL diode D_(EL).

FIG. 10A is a cross-sectional view of the formation of a full-colorelement layer on a substrate in a process of fabricating an organicelectroluminescent diode substrate for a dual-panel type organicelectroluminescent device according to the third embodiment of thepresent invention. Referring to FIG. 10A, a second substrate 400includes a pixel region P, and a non-pixel region NP at a boundary ofthe pixel region P. A full-color element layer FE is formed on thesecond substrate 400. The full-color element layer FE includes a blackmatrix 402, a color filter layer 404 and a color changing medium 405.The black matrix 402 is located in the non-pixel region NP and includesone of a black resin and a chrome based material. An overcoat layer 406is formed on the entire surface of the full-color element layer FE.

FIG. 10B is a cross-sectional view of the molding of a resin layer on anelectrode in a process of fabricating an organic electroluminescentdiode substrate for a dual-panel type organic electroluminescent deviceaccording to the third embodiment of the present invention. Referring toFIG. 10B, a first electrode 408 is formed on the entire surface of theovercoat layer 406. When the first electrode 408 acts as an anode, itincludes a conductive material having a high work-function such asindium tin oxide (ITO).

A resin solution is coated on the entire surface of the first electrode408 to form a resin solution layer 409. The resin solution layer 409 mayinclude a transparent organic insulating material, such as acrylicresin. Then, a mold M3 is pressed on the resin solution layer 409according to a predetermined pressure. The mold M3 includes a recessedportion RP alternating with a protruding portion PP. The recessedportion RP has the same height H3 as the protruding portion PP. As shownin FIG. 10B, when the recessed portion RP and the protruding portion PPof the mold M3 face the resin solution layer 409, the width of therecessed portion RP gradually decreases toward the second substrate 400and the width of the protruding portion PP gradually increases towardthe second substrate 400.

The resin solution layer 409 is solidified by heating under apredetermined pressure. The heating process may be performed at atemperature higher than a boiling point and a transition temperature ofthe resin solution layer 409. For example, the predetermined pressuremay be within 1 N/cm² to 100 N/cm². The pressing process is similar tothe one described in reference to FIG. 7B.

FIG. 10C is a cross-sectional view of the formation of a separator on anelectrode in a process of fabricating an organic electroluminescentdiode substrate for a dual-panel type organic electroluminescent deviceaccording to the third embodiment of the present invention. Referring toFIG. 10C, the mold M3 (shown in FIG. 10B) is removed from the secondsubstrate 400 leaving a solidified resin solution layer on the firstelectrode 408. The solidified resin solution layer on the firstelectrode 408 forms a separator 410 on the first electrode 408 in thenon-pixel region NP.

The separator 410 has a first portion BB and a second portion SS. Thefirst portion BB is closer to the second substrate 400 than the secondportion SS. A first width W1 of the first portion BB is larger that asecond width W2 of the second portion SS. A cross-sectional of thesecond portion SS decreases gradually from both end sides toward amiddle part of the cross-sectional. A side gap K of a top side of thesecond portion SS and a bottom side of the first portion BB may be about2 micrometers.

FIG. 10D is a cross-sectional view of the formation of an organicelectroluminescent layer on an electrode in a process of fabricating anorganic electroluminescent diode substrate for a dual-panel type organicelectroluminescent device according to the third embodiment of thepresent invention. Referring to FIG. 10D, at least one organic EL layer412 and a second electrode 414 are sequentially formed on the firstelectrode 408 in the pixel region P surrounded by the separator 410. Theorganic EL layer 412 includes red, green and blue EL layers (not shown)in the pixel regions P in repeating order.

The at least one organic EL layer 412 may include a single layer ormultiple layers. When the at least one organic EL layer 412 includesmultiple layers and the first electrode 414 acts as the anode, the atleast one organic EL layer 412 includes a hole transporting layer 412 aon the first electrode 414, an emitting layer 412 b and an electrontransporting layer 412 c. When the second electrode 414 acts as acathode, it may include a metallic material, such as calcium (Ca),aluminum (Al) and magnesium (Mg) and lithium fluorine/aluminum (LiF/Al).

FIG. 11 is a scanning electron microscopic view of an exemplaryseparator manufactured in accordance with the third embodiment of thepresent invention. Referring to FIG. 11, the separator includes anovolac solution dissolved in ethanol at a concentration of 15% inweight. The resin solution layer is pressed under a pressure of about 10N/cm² and heating is performed at about 130 degrees Celsius while theresin solution layer is pressed by the mold. Moreover, the first widthof the first portion is about 5 micrometers.

FIGS. 12A and 12B are cross-sectional views of an array substrate for adual-panel type organic electroluminescent device according to anembodiment of the present invention. Hereinafter, a method offabricating an array substrate for a dual-panel type OELD device will bedescribed in reference to FIGS. 12A and 12B. Referring to FIGS. 12A and12B, a pixel region P on a first substrate 300 includes a switchingregion S and a driving region D. A switching thin film transistor T_(S)and a driving thin film transistor TD are formed on the first substrate300 including the switching region S and the driving region D,respectively. The switching thin film transistor T_(S) includes aswitching gate electrode 302, a switching active layer 310, a switchingsource electrode 318, and a switching drain electrode 320. Similarly,the driving thin film transistor T_(D) includes a driving gate electrode304, a driving active layer 314, a driving source electrode 322, and adriving drain electrode 324.

The switching gate electrode 302 is connected to a gate line (notshown). The switching source electrode 318 is connected to a data line(not shown). The switching drain electrode 320 is connected to thedriving gate electrode 304. The driving source electrode 322 isconnected to a power line 326. A gate insulating layer 306 is formedbetween the gate electrodes 302 and 304 and the active layers 310 and314.

A first passivation layer 325 is formed between the switching thin filmtransistor T_(S) and the power line 326. A first contact hole 327 isprovided through the first passivation layer 325. The first contact hole327 exposes a portion of the driving source electrode 322. The powerline 326 is connected to the driving source electrode 322 via the firstcontact hole 327.

A second passivation layer 328 is formed on the entire surface of thepower line 326 and the switching thin film transistor Ts. A secondcontact hole 329 is provided through the first passivation layer 325 andthe second passivation layers 328. The second contact hole 329 exposes aportion of the driving drain electrode 324.

A connection electrode 350 is formed on the second passivation layer328. The connection electrode 350 is connected to the driving drainelectrode 324 via the second contact hole 329. The connection electrode350 includes an organic pattern 350 a having a predetermined height anda metallic material layer 350 b covering the organic pattern 350 a.Although not shown, the connection electrode 350 electrically connectsthe organic EL diode and the array element layer by attaching the firstand second substrates 300 and 400. For example, the connection electrode350 connects the second electrode 400 and the driving thin filmtransistor T_(D).

In accordance with embodiments of the present invention, the OELD devicemay have a high aperture ratio because the OELD device is a top emissiontype. Undesired effects due to the fabricating process of the organic ELdiode can be prevented because the array layers are independently formedon respective substrates. Accordingly, overall production yieldincreases. A separate buffer layer is not required because the OELDdevice includes a separator, a second portion of which functions as abuffer layer. The molding of the separator can be performed without anymask process, thereby reducing processing time and cost.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the organicelectroluminescent display device and fabricating method thereof of thepresent invention without departing from the spirit or scope of theinvention. Thus, it is intended that the present invention cover themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

1. A method of fabricating an organic electroluminescent display device,comprising: forming a first electrode in a pixel region of a substrate,the substrate including a non-pixel region at a boundary of the pixelregion; forming a resin solution layer by coating a resin solution onthe first electrode; pressing a mold on the resin solution layer, themold having a recessed portion alternating with a protruding portion,the recessed portion having the same height as the protruding portion,the recessed portion and the protruding portion facing the resinsolution layer, a first width of the recessed portion being larger thana second width of the recessed portion, the first width being closer tothe resin solution layer than the second width; solidifying the resinsolution layer by heating; removing the mold from the solidified resinsolution layer forming a separator in the non-pixel region on thesubstrate, the separator having a first portion having the first widthand a second portion having the second width, the first portionoverlapping edges of the first electrode, and the second portion withinthe non-pixel region; forming an organic electroluminescent layer on thefirst electrode in the pixel region surrounded by the separator; andforming a second electrode on the organic electroluminescent layer andthe separator.
 2. The method according to claim 1, wherein the resinsolution layer is formed by one of dipping the substrate in the resinsolution and dropping the resin solution on the substrate.
 3. The methodaccording to claim 1, wherein the mold is slightly pressed on the resinsolution layer to avoid contacting a bottom side of the resin solutionlayer.
 4. The method according to claim 1, wherein heating is performedat a temperature higher than a boiling point and a transitiontemperature of the resin solution.
 5. The method according to claim 1,wherein the mold is formed by molding an elastomeric.
 6. The methodaccording to claim 1, further comprising forming an array element layerhaving a thin film transistor between the substrate and the firstelectrode connected to the thin film transistor.
 7. A method offabricating an organic electroluminescent display device, comprising:forming a first electrode in a pixel region of a substrate, thesubstrate including a non-pixel region at a boundary of the pixelregion; forming a resin solution layer by coating a resin solution onthe first electrode; pressing a mold on the resin solution layer, themold having a recessed portion alternating with a protruding portion,the recessed portion having the same height as the protruding portion,the recessed portion and the protruding portion facing the resinsolution layer, the recessed portion and the protruding portion havingrespective square shapes; solidifying the resin solution layer bysequentially heating at two different temperatures including a firsttemperature smaller than or equal to a boiling point of the resinsolution and a second temperature higher than the first temperature;removing the mold from the solidified resin solution layer forming aseparator in the non-pixel region on the substrate, the separator havinga first portion having a first width and a second portion having asecond width smaller than the first width, the first portion overlappingedges of the first electrode, and the second portion within thenon-pixel region; forming an organic electroluminescent layer in thepixel region surrounded by the separator; and forming a second electrodeon the organic electroluminescent layer and the separator.
 8. The methodaccording to claim 7, wherein a side gap between the first width and thesecond width is between 2 and 10 micrometers, and a thickness of thefirst portion of the separator is less than about 300 nanometers.
 9. Themethod according to claim 7, wherein the resin solution layer is formedby one of dipping the substrate in the resin solution and dropping theresin solution on the substrate.
 10. The method according to claim 7,wherein the mold is slightly pressed on the resin solution layer toavoid contacting a bottom side of the resin solution layer.
 11. Themethod according to claim 7, wherein the mold is formed by molding anelastomeric.
 12. The method according to claim 7, further comprisingforming an array element layer having a thin film transistor between thesubstrate and the first electrode connected to the thin film transistor.13. A method of fabricating an organic electroluminescent device,comprising: forming a first electrode on an entire surface of a firstsubstrate including a pixel region and a non-pixel region at a boundaryof the pixel region; form a resin solution layer by coating a resinsolution on an entire surface of the first electrode; pressing a mold onthe resin solution layer under a predetermined pressure, the moldincluding a recessed portion alternating with a protruding portion, therecessed portion having the same height as the protruding portion, therecessed portion and the protruding portion of the mold facing the resinsolution layer, a width of the recessed portion gradually decreasingtoward the substrate and a width of the protruding portion graduallyincreasing toward the substrate; solidifying the resin solution layer byheating; removing the mold from the solidified resin solution layerforming a separator in the non-pixel region on the substrate, theseparator having a first portion having a first width and a secondportion having a second width smaller than the first width, the firstportion closer to the substrate than the second portion, across-sectional of the second portion decreasing gradually from both endsides thereof toward a middle part thereof; and sequentially forming anorganic electroluminescent layer and a second electrode on the firstelectrode, the organic electroluminescent layer and the second electrodedivided into a region corresponding to the pixel region by theseparator.
 14. The method according to claim 13, wherein the resinsolution layer is formed by one of dipping the substrate in the resinsolution and dropping the resin solution on the substrate.
 15. Themethod according to claim 13, wherein the mold is slightly pressed onthe resin solution layer to avoid contacting a bottom side of the resinsolution layer.
 16. The method according to claim 13, wherein heating isperformed at a temperature higher than a boiling point and a transitiontemperature of the resin solution.
 17. The method according to claim 13,wherein the mold is formed by molding an elastomeric.
 18. The methodaccording to claim 13, wherein the predetermined pressure is within 1N/cm² to 100 N/cm².
 19. An organic electroluminescent display device,comprising: a substrate, including a pixel region and a non-pixel regionat a boundary of the pixel region; a first electrode on the substrate inthe pixel region; a separator over the first electrode, the separatorlocated in the non-pixel region, the separator including a first portionhaving a first width and a second portion having a second width smallerthan the first width, the first portion overlapping edges of the firstelectrode, and the second portion within the non-pixel region; anorganic electroluminescent layer over the separator in the pixel regionsurrounded by the separator; and a second electrode on an entire surfaceof the organic electroluminescent layer and the separator.
 20. Thedevice according to claim 19, wherein a side gap between the first widthand the second width is between 2 micrometers to 10 micrometers.
 21. Thedevice according to claim 19, wherein a thickness of the first portionof the separator is less than about 300 nanometers.
 22. The deviceaccording to claim 19, wherein a side of the second portion isperpendicular to a surface of the substrate.
 23. An organicelectroluminescent display device, comprising: a first substrate,including a pixel region and a non-pixel region at a boundary of thepixel region; a first electrode on an entire surface of the firstsubstrate; a separator over the first electrode in the non-pixel region,the separator having a first portion having a first width and a secondportion having a second width smaller than the first width, across-sectional of the second portion decreasing gradually from both endsides thereof toward a middle part thereof; an organicelectroluminescent layer over the separator, the organicelectroluminescent layer in the pixel region; and a second electrode onthe organic electroluminescent layer, the second electrode correspondingto the organic electroluminescent layer.
 24. The device according toclaim 23, wherein a side gap of a top side of the second portion and abottom side of the first portion is about 2 micrometers.
 25. The deviceaccording to claim 23, wherein the first electrode, the organicelectroluminescent layer and the second electrode form an organicelectroluminescent diode.
 26. The device according to claim 25,comprising an array element layer including a switching thin filmtransistor and a driving thin film transistor connected to the switchingthin film transistor on a second substrate facing and spaced apart fromthe first substrate, and a connection electrode connecting the arrayelement layer and the organic electroluminescent diode between the arrayelement layer and the organic electroluminescent diode.
 27. The deviceaccording to claim 26, wherein the array element layer further includesa gate line, a data line crossing the gate line and a power linecrossing one of the gate line and the data line, the gate line and thedata line connected to the switching thin film transistor, and the powerline connected to the driving thin film transistor.
 28. The deviceaccording to claim 23, wherein the first electrode acts as an anode. 29.The device according to claim 28, wherein the first electrode includesindium tin oxide (ITO).
 30. The device according to claim 28, whereinthe organic electroluminescent layer includes a hole transporting layeron the first electrode.
 31. The device according to claim 23, whereinthe second electrode acts as a cathode.
 32. The device according toclaim 31, wherein the second electrode includes one of calcium (Ca),aluminum (Al) and magnesium (Mg) and lithium fluorine/aluminum (LiF/Al).33. The device according to claim 31, wherein the organicelectroluminescent layer includes an electron transporting layer on thesecond electrode.